1. Field of the Invention
The present invention relates to a computer program product, system, and method for restoring deduplicated data objects from sequential backup devices.
2. Description of the Related Art
In a network backup environment, client systems back-up their data to a backup server over a network. The backup server maintains a database of backup objects providing information on backup objects stored in backup storage pools. The client systems may restore data objects from the backup objects maintained by the backup server.
The backup client and server may implement data deduplication, which removes redundant data during a backup operation to optimize storage space and conserve network bandwidth. The backup operation may back-up data in chunks or extents of data, such that if multiple data objects share the same extent, then only one instance of the extent is stored in backup storage.
Deduplication during storage backup activities can be performed at the data source (client), data target (server), or on a deduplication appliance connected to the backup server. The restoration of deduplicated data from the server to the client involves reconstruction of the data from deduplicated chunks or extents. In current systems, the deduplicated data is stored on disk, and the backup sever will access the extents for data objects to restore from the disk, and then return full data objects to the client, including objects that have common extents. Even if the same extent is found in many data objects (or even in the same object) selected for restore, that chunk or extent will be restored and transmitted from the server to the client multiple times. The backup server may access the extents from disk in any order due to the random access nature of the disk-based storage.
There is a need in the art for improved techniques for handling the restoration of data objects in different storage environments.